fm-rds-tx/internal/offline/generator_test.go

package offline

import (
	"math"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	cfgpkg "github.com/jan/fm-rds-tx/internal/config"
)

func TestGenerateFrame(t *testing.T) {
	g := NewGenerator(cfgpkg.Default())
	frame := g.GenerateFrame(50 * time.Millisecond)
	if frame == nil {
		t.Fatal("expected frame")
	}
	if len(frame.Samples) == 0 {
		t.Fatal("expected samples")
	}
}

func TestGenerateFrameFMIQ(t *testing.T) {
	cfg := cfgpkg.Default()
	cfg.FM.FMModulationEnabled = true
	g := NewGenerator(cfg)
	frame := g.GenerateFrame(10 * time.Millisecond)

	// With FM modulation, IQ samples should have magnitude ~1
	for i := 100; i < len(frame.Samples) && i < 200; i++ {
		s := frame.Samples[i]
		mag := math.Sqrt(float64(s.I)*float64(s.I) + float64(s.Q)*float64(s.Q))
		if math.Abs(mag-1.0) > 0.01 {
			t.Fatalf("sample %d: IQ magnitude=%.4f, expected ~1.0", i, mag)
		}
	}
}

func TestGenerateFrameCompositeOnly(t *testing.T) {
	cfg := cfgpkg.Default()
	cfg.FM.FMModulationEnabled = false
	g := NewGenerator(cfg)
	frame := g.GenerateFrame(10 * time.Millisecond)

	// Without FM modulation, Q should be 0
	for i := 0; i < len(frame.Samples) && i < 100; i++ {
		if frame.Samples[i].Q != 0 {
			t.Fatalf("sample %d: Q=%.6f, expected 0 in composite mode", i, frame.Samples[i].Q)
		}
	}
}

func TestWriteFile(t *testing.T) {
	cfg := cfgpkg.Default()
	out := filepath.Join(t.TempDir(), "test.iqf32")
	cfg.Backend.OutputPath = out
	g := NewGenerator(cfg)
	if err := g.WriteFile(out, 20*time.Millisecond); err != nil {
		t.Fatalf("WriteFile failed: %v", err)
	}
	info, err := os.Stat(out)
	if err != nil {
		t.Fatalf("expected output file: %v", err)
	}
	if info.Size() == 0 {
		t.Fatal("expected non-empty file")
	}
}

func TestSummaryUsesToneFallback(t *testing.T) {
	cfg := cfgpkg.Default()
	cfg.Audio.InputPath = ""
	g := NewGenerator(cfg)
	summary := g.Summary(10 * time.Millisecond)
	if !strings.Contains(summary, "source=tones") {
		t.Fatalf("unexpected summary: %s", summary)
	}
}

func TestSummaryUsesFallbackLabelOnBadWAV(t *testing.T) {
	cfg := cfgpkg.Default()
	cfg.Audio.InputPath = "missing.wav"
	g := NewGenerator(cfg)
	summary := g.Summary(10 * time.Millisecond)
	if !strings.Contains(summary, "source=tone-fallback") {
		t.Fatalf("unexpected summary: %s", summary)
	}
}

func TestSummaryContainsPreemph(t *testing.T) {
	cfg := cfgpkg.Default()
	cfg.FM.PreEmphasisUS = 50
	g := NewGenerator(cfg)
	summary := g.Summary(10 * time.Millisecond)
	if !strings.Contains(summary, "preemph=50µs") {
		t.Fatalf("unexpected summary: %s", summary)
	}
}

func TestSummaryContainsFMIQ(t *testing.T) {
	cfg := cfgpkg.Default()
	cfg.FM.FMModulationEnabled = true
	g := NewGenerator(cfg)
	summary := g.Summary(10 * time.Millisecond)
	if !strings.Contains(summary, "FM-IQ") {
		t.Fatalf("unexpected summary: %s", summary)
	}
}

func TestLimiterPreventsClipping(t *testing.T) {
	cfg := cfgpkg.Default()
	cfg.FM.LimiterEnabled = true
	cfg.FM.LimiterCeiling = 1.0
	cfg.FM.FMModulationEnabled = false // raw composite to check levels
	cfg.Audio.ToneAmplitude = 0.9      // high amplitude to exercise limiter
	cfg.Audio.Gain = 2.0
	cfg.FM.OutputDrive = 1.0
	g := NewGenerator(cfg)
	frame := g.GenerateFrame(50 * time.Millisecond)

	for i, s := range frame.Samples {
		if math.Abs(float64(s.I)) > 1.01 {
			t.Fatalf("sample %d: composite=%.4f exceeds ceiling", i, s.I)
		}
	}
}